In a photographing apparatus, such as a camera, etc., which uses an image sensor, if a high-frequency component that is greater than that of the sampling frequency of the image sensor is included in an object image formed through a photographing lens, moire and false color that does not originally exist in the object image can occur, thereby deteriorating the photographed image.
Patent Literature Nos. 1 through 3 each disclose technology in which the occurrence of moire and false color can be prevented by inserting an optical low-pass filter into the optical path of a photographing optical system to thereby attenuate the high-frequency component of the object image that is formed through the photographing lens. However, optical low-pass filters are expensive and also deteriorate the resolution and contrast.
Patent Literature No. 3 discloses a camera which takes a plurality of photographs at different spatial frequency characteristics while changing the spatial frequency characteristics of the optical low-pass filter.
However, in the camera of Patent Literature No. 3, since the optical low-pass filter is constantly inserted into the optical path of the photographing optical system, even if the spatial frequency is set in order to obtain, e.g., a high-resolution photographed image, a reduction in resolution and contrast of the optical low-pass filter itself occurs to some extent, so that a photographed image having a maximally improved resolution and contrast cannot be obtained.
Furthermore, in an actual on-site photographic shoot, even if the photographer is concerned with occurrence of moire and false color and changes the spatial frequency of the optical low-pass filter when carrying out a photographing operation, sometimes no moire or false color occurs. In such a case, the photographer would regret this result thinking, “if moire or false color is not going to occur, I wanted to obtain a photographic image having maximally improved resolution and contrast, without attenuating the high-frequency component of the object image”. However, in the camera of Patent Literature No. 3, since the optical low-pass filter is always inserted into the optical path of the photographing optical system, a photographic image having maximally improved resolution and contrast cannot be obtained without attenuating the high-frequency component of the object image.
Furthermore, in recent years, due to cameras becoming highly sophisticated and multi-functionalized, an extremely vast variety of photographers' photographic preferences exist. For example, there is a photographer's photographic preference in which there is a “desire to obtain, with respect to photographic images having similar compositions, a photographed image having maximally improved resolution and contrast while allowing moire and false color to occur, and a photographed image in which the occurrence of moire and false color is prevented while allowing reduction in resolution and contrast to some extent”. However, the camera of Patent Literature No. 3 cannot be applied in a versatile manner with respect to such a photographer's photographic preference.